The invention relates to a method for producing selected mass spectra with the use of electromagnetic radiation which is directed onto sample material through an optical system for vaporization, destruction, excitation and/or ionization in the microrange wherein the expanse of the irradiated regions of the sample is adjustable by selection of the energy density of the radiation and the released particles are detected.
A laser microanalysis device is known (German Offenlegungsschrift [laid-open patent application] No. 2,141,387) in which biological material is microanalyzed and, in order to cause the irradiated area to be smaller than the cell size, the power density of the radiation is set so that when focused in the diffraction maximum of zero order it lies above, and in the diffraction maximum of the first order it lies below, the limit at which a sudden increase in absorption takes place in the test sample material. This controls only the spatial resolution of the process but does not influence the shape or composition, respectively, of atomic and/or molecular spectra, because this composition is not necessarily (possibly accidentally) coupled with the sudden absorption behavior.
It is also known (BIST-CEA No. 204, June, 1975) to make a mass spectrometric analysis of test samples by means of an incident laser light method wherein the detection of atomic spectra is desired.